BATTLE CREEK, Mich. (WWJ/AP) - Three boys ages 11 to 13 have been charged with sexually assaulting two younger boys at a southern Michigan garage that police suspect was burned to destroy evidence.

The suspects are being held at the Calhoun County Juvenile Home on juvenile first-degree criminal sexual conduct charges. According to authorities, they're accused of repeatedly assaulting the 6- and 8-year-olds in Battle Creek over the course of about a month.

The younger boys told their mother about the assaults June 12, the day of the fire, after she said she "noticed unusual behavior" the night before.

According to the Battle Creek Enquirer, police said the first incident of assault was at the home of the victims when one of the boys locked both young boys inside a closet with him.

Police Chief Jim Blocker said investigators think the fire was set intentionally in the garage -- where the boys said they were held down by their arms and legs and assaulted -- in a cover-up attempt.

The suspects, however, told officers the fire started accidentally while they were smoking marijuana and dropped a cigarette on a mattress. They told police that they grabbed a bucket filled with gasoline; and, thinking it was water, threw it on the fire, according to the newspaper.

As an investigation continues, police believe there may be more victims, possibly even younger, and more charges to come in the case. Anyone with information should call Battle Creek police at 269-966-3322.